Figure 3.

p63 suppresses pro-apoptotic pathways during early involution. (a and b) Immunoblot analysis of apoptosis-related proteins in whole mammary glands at day 3 of involution. Two representative experiments out of four (a) and quantification from all four independent experiments analyzing a total of seven p63+/+ and five p63+/− mice (b) are shown. Mean±S.E.M., *P<0.05. L10, lactation day 10, serves as a negative control for apoptosis. (c and d) Upregulation of oncostatin M (OSM), but not other known activators of pStat3, as well as downregulation of NRG1 and NRG2, known activators of the ErbB/pStat5 axis, in p63+/−compared with p63+/+ mammary epithelial cells. qRT-PCR analysis was done on mammary epithelial cells freshly isolated from littermate females at day 1 and day 3 of involution. Mean±S.E.M., *P<0.05, **P<0.01